ive mad models before and they have worked fine so i dont know what your talking about.
anyway you cant know cus you said they have to be called Mountpoint and muzzlepoint, you got them wrong
I do know as I have already made add-ons before, models, scripts and all. The blue circles are called joints, they are used for various things (animations, emitter positions, etc.). Naming the joints as such allows for them to be used properly in Blockland.
Mountpoint determines where it shall be held by the player,
Muzzlepoint determines where the you would fire/attack from.